Background During ventilatory assistance, optimization of settings is critical to allow a personalized support and avoid over- or under-assistance. But little data are available in clinical practice to guide the adjustment of the support. In adults, esophageal pressure (PES) has been shown to be a reliable surrogate of pleural pressure (PPL) and clinical studies suggest that PES may be useful to guide the management of mechanical ventilation. In children, the PES measurement could have similar potential benefits, but beforehand the reliability of PES to estimate PPL needs to be assessed.